Indication means for light signals



L. F. HOWARD.

INDICATi ON MEANS FOR LlGH-T SlGNALS. APPLICATION FILED MAR. 2. 1921.

1,429,141, Patent eds efit. 12,1922.

Patented Sept. 12, 1922,

Ulhitll a ain LEMUEL F. HOWARD, or EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOB. are THE UNION SWITCH & SIG-NAIL COMPANY, or SWISSVALE, PENNSYLVANIA, a con- PORATION OF PENNSYLVANIA.

INDICATION MEANS FOR LIGHT SIGNALS.

Application filed March 2,

T 0 all whom it may concern:

Be it known that I, LEMU'EL F. HOWARD, a citizen of the United States, residing at Edgewood Borough, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Indication Means for Light Signals, of which the following is a specification.

My invention relates to signals of the i type comprising lamps, and has for an object the provision of means for indicating illumination of the lamp at a point remote from-the lamp.

Apparatus embodying my invention is particularly well adapted for use in connection with railway signals which are controlled by the levers of interlocking machines. In systems of this character the lever is usually provided with a lock which is known as an indication device. One' feature of my invention is the provision of means for controlling this look in accordance with the light which is actually emitted by one of the lamps in the signal governed by such lever.

I will describe several forms of apparatus embodying my invention, and will then point out the novel features thereof in claims. c i

In the accompanying drawings, Fig. 1 is diagrammatic view showing one form of apparatus embodying my invention, the lever lock being controlled directly by a light responsive cell which is exposed to the light from one of the signal lamps Fig, 2 is a view showing a modification of the apparatus shown in Fig. 1, the lever lock in this instance being controlled by a relay which in turn is governed by the light responsive cell. Fi 3 is a diagrammatic view showing the application of the- Wheatstone bridge principle to apparatus embodying my invention. Fig. 4 is a diagrammatic view showing one manner in which the potentiomet'er principle may be applied to apparatus embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referrin first to Fig. 1, the reference character designates a signal comprising two electric lamps G and R which lamps when illuminated are adapted to indicate proceed and stop, respectively. These 1921. Serial No. 4.49,144.

and the supply of this current is controlled v by a manually operable lever A. The primary 6 0f the transformer T is constantly supplied with alternating current from a suitable source which is not shown in the drawing.

The supply of current to the signal lamps G and R is controlled by a contact 4 which is attached to lever A, and which engageswith a contact 5 or with a contact 5, ac-

cording as the lever is in one position or another. As shown in the drawing, the lever A is in the right hand extreme position wherein contact l5 is closed. Lamp G is then supplied with current through a circuit which passes from the right hand terminal of transformer secondary 2, through wire 7, contact 45 wire 8, lamp G, and wires 9, 10 and 11 to transformer secondary 2. When the lever- A is shifted to the left, the stop lamp R becomes illuminated by virtue of a circuit which passes from transformer secondary 2, through wire 7, contact 45 wire 12, lamp and -11 to secondary 2.

The lever A will usually be one of a plurality of similar levers in an interlocking machine, and, as is well understood, in apparatus of this nature the various levers are usually inter-controlled by what is known as mechanical locking. For this reason it is desirable that a complete move ment of the lever A to its extreme left hand position should be prevented until an indication is given at the lever that the stop lamp R has become illuminated. To accomplish this the lever is provided with a lock or indication device B comprising a shoulder 15 on the lever, a dog 14 normally in position to engage with this shoulder, and a magnet 16 arranged when energized to lift the dog 14 out of the path of the shoulder 15. The parts are so proportioned that when the lever is shifted to the left the shoulder 15 engages the dog 14: after contact fr-5 is closed, and that this contact remains- R and wires 13, 1O

, lamp is exposed to'the light emitted by the stop R. The cell F has the characteristic that its electrical resistance varies in accordance with changes .in the intensity of the light to which it is exposed. A cell having this characteristic may be made, for example, of selenium, stibnite, or copper oxide, or may be what is known as a photoelectric cell, in which the active material is an alkali metal. The precise nature of this cell and the substance of which it is composed, form no part of my present invention. The only essential feature of construction is that this cell shall be so located as to receive light from the lamp R but not from any other source.

The light responsive cell F is connected in series with the magnet 16 and the secondary 3 of transformer T, the circuit being from the ri ht hand terminal of this secondary throug wire 19, magnet 16, wire 18, cell F, and wire 17 to the secondary 3. The parts of this circuit are so adjusted and proportioned that when the lamp R is dark, so that the resistance of cell F is comparatively high, the current supplied to magnet 16 is not suflicientto cause this magnet to lift the dog 14 out of the path of shoulder 15. When lamp R becomes illuminated, however, so that the resistance of the light responsive cell F is decreased-,the current which is then supplied to magnet 16 is sufiicient to elevate the dog 14, so that the movement of lever A to its left hand extreme position may be completed.

If desired, a visual indicator may be provided at the lever A to show the operator whether the lamp G or the lamp R of signal S is illuminated. This indicator, as here shown, comprises two incandescent lamps G and R, which are supplied with current from the transformer secondary 2, through a contact 21 which is operated by the armature of magnet 16. When signal lamp G is illuminated, the contact 21 is in its lowest position, so that current is supplied to indicator lamp G through wires 7 and 20, contact 21, lamp G and wires 22 and 11 to transformer secondary 2. When signal lamp It becomes illuminated, the consequent elevation of the armature of magnet 16 ralses contact 21 to its hi hest position wherein the indicator lamp R becomes energized through a circuit which will be obvious from the drawing? Referring now to ig. 2, the apparatus shown herein is similar to that shown in Fig. 1, except that the magnet 16 of the .lever lock B is controlled by. a relay Q5,

which in turn is governed by the light responsive device F.

The relay Q comprises two windings 23 and 24. The winding 24 is constantly connected across transformer secondary 3, the

circuit being from this secondary through -comprises two lamps, G and BC.

to answer wire 34, relay winding 23, and wires 28,

29 and 30 to secondary 3. Relay Q and the circuits associated with its windings are so designed and proportioned that when the cell F is dark, contact 37 is open, but that when the cell F is exposed to light rays from the lamp R this contact 37 is closed. As is well understood, the relay Q may be so designed that the greater part of the ener required for operating this relay is furnished by the winding 24 and that winding 23 need supply only a comparatively small amount of controlling energy. Tt follows that the light responsive cell F need carry only a comparatively small amount of current, and that this current can be considerably weaker than the current which must be transmitted through the cell F in F/Tagnet 16 is controlled by contact 37 of relay Q, the circuit for this magnet being from transformer secondary 3, through wires 25, 31 and 36, contact 37, wire 38, magnet 16 and wires 39 and 30 to secondary 3.

The operation of the apparatus shown in Fig. 2 will be apparent from the foregoing without further explanation. If desired, a visual indicator may be provided at the lever A, and as here shown, this indicator These lamps are controlled by an additional contact 21, operated by relay Q. The circuit for these lamps is from transformer secondary 3, through wires 25, and 41, lamp G or to secondary 3. It will be apparent that indicator lamp G will be illuminated when signal lamp G is illuminated, and that, similarly, the indicator lamp R will be illuminated when the signal lamp R is illuminated.

Referring now to Fig. 3, T have here shown diagrammatically one way in which the Wheatstpne bridge principle may be ap plied to the apparatus shown in Figs. 1 and 2. The light responsive cell F is included in one arm of the bridge and is balanced by a fixed resistance 40 in the other arm. The connecting member of the bridge includes the magnet winding 16 of Fig. 1 or the relay winding 23 of Fig. 2 in place of the galvanometer which .is generally used in connection with the Wheatstone bridge network of circuits. In this form'of my invention the parts of the apparatus may be so adjusted that when the cell F is dark there is no current supplied to the winding 16 or 23. When the cell F is illuminated, however, the electromotive forces are unbalanced, so that contact 21, and wires 42, 29 and 30 mama].

current then flows in winding 16 or 23. As

' is well understood, the apparatus may be designed that a comparatively small change in resistance of the cell F will cause a comparatively large amount of current to How through the magnet winding 16 or the relay winding 23.

Referring now to Fig. 4, I have here shown one manner in which the potentiometer principle may be applied to the apparatus shown in Figs. 1 and 2. In this structure a resistance 43 is connected across the terminals of secondary 2 of transformer T. The light responsive device F is included in circuit with transformer secondary 3, and with the magnet 16 or the relay winding 23 according as the scheme is applied to the apparatus shown in Fig. 1 or Fig. 2.

One terminal of this circuit is connected with one terminal of secondary 2, whereas the other terminal of the circuit is connected with such a point on resistance 43 that whenthe cell F is. dark, no current flows in winding 16 or 23. When cell F is exposed to light, however, due to the illumi nation of the stop lamp R, the resistance of the circuit including this cell is lowered so that current of considerable amplitude flows through winding 16 or 23.

Although I have herein shown and described only a few forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: v

1. In combination, a railway signal comprising a lamp, a lever of an interlocking machine, means controlled by a partial movement of said lever for causing said lamp to become illuminated, a lock for preventing ccmpletion of the movement of said lever, and means responsive to the light emitted by said lamp for releasing saidlock.

2. In combination, a railway signal comprising a lamp, a lever ofan interlocking machine, means controlled by a partial movement of said lever for causing said lamp to become illuminated, a lock for preventing completion of the movement of said lever, a cell exposed to the light emitted by said lamp and having thecharacteristic that its electrical resistance varies with changes in the intensity of light, and means controlled by said cell for releasing said look when said lamp is illuminated.

3. A combination, a railway signal comprising a lamp, a lever of an interlockin machine, means controlled by a partia movement of said lever for causing said lamp to become illuminated, a lock for preventing completion of the movement or said lever, a cell exposed to the light emitted become illuminated, a lock by said lamp and having the characteristic that its electrical resistance varies with changes in the intensity of light, and a circuit including said cell and a source of current for controlling said lock.

4. In combination, a railway signal comprising a lamp, a lever of an interlocking machine, means controlled by a partial movement of said lever for causin said lamp to For preventing completion of the movement of said lever, a cell exposed to the light emitted by said lamp and having the characteristic that its electrical resistance varies with changes in the intensity of light, a/magnet for releasing said lock, and a circuit including said cell and said magnet and a source of current.

5. In combination, a railway signal comprising a lamp, a lever for controlling the illumination of said lamp,- and means including a cell responsive to the light emitted by said lamp for governing said lever.

6. In combination, a railway signal comprising a lamp, a-lever for controlling the ,7 lamp, a cell exposed to the light emitted by said lamp and having the characteristic of varying in electrical resistance with changes in the intensity of light to which it is exposed, and means controlled by said cell for indicating illuminatiom of said lamp ata point remote from the lamp.

9. In combination. a signal comprising a lamp, a cell exposed to the light emitted by said lamp and having an electrical resistance of one value when thelamp is illuminated and another value when the lamp is extinguished, and means cont-rolled by theresistance of said cell for indicating illumination of said lamp at a point remote from the lamp.

10. In combination, a signal comprising a lamp, and means for indicating illumination of said lamp at a remote point comprising a cell responsive to the light emitted by the lamp.

11. In combination, a signal comprising a lamp, and means for indicating illumination of said lamp 'at a remote point comprising a cell exposed to the light emitted by said lamp and having the characteristic of varying in electric resistance with variations in the intensity of the light to which it is exposed.

12. In combination, a signal comprising a lamp, a cell exposed to the light emitted by said lamp and havingthe characteristic of varying in electrical resistance with variations in the intensity of light to which it is exposed, a circuit including said cell and a source of current, and indicating means controlled by said circuit.

13. In combination, a railway signal comprising a lamp, a lever for controlling the illumination of said lamp, a cell responsive to the light emitted by said lamp, a lock for governing said lever, a relay controlling said lock and having two windings, a circuit for one winding including said cell and a source of current, and means for supplying the other winding with current.

14:. lln combination, a signal comprising a lamp a cell responsive to the light emitted by said lamp, a relay having two co -acting windings, a circuit for one win'ding includin said cell and a source of current, a circuit for the other relay winding including a source of current, and means controlled by said relay for indicating illumination of said lamp at a point remote from the lamp.

lln testimony whereof I afiix my signature.

LEMUEL 1F. HOWARD. 

